// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/syslog_logging.h"
#include "base/debug/stack_trace.h"

#if defined(OS_WIN)
#include "base/bind.h"
#include "base/callback_helpers.h"
#include "base/win/eventlog_messages.h"

#include <windows.h>
#elif defined(OS_LINUX)
#include <syslog.h>
#endif

#include <cstring>
#include <ostream>
#include <string>

namespace logging {

#if defined(OS_WIN)

namespace {
    std::string* g_event_source_name = nullptr;
}

void SetEventSourceName(const std::string& name)
{
    DCHECK_EQ(nullptr, g_event_source_name);
    g_event_source_name = new std::string(name);
}
#endif // defined(OS_WIN)

EventLogMessage::EventLogMessage(const char* file,
    int line,
    LogSeverity severity)
    : log_message_(file, line, severity)
{
}

EventLogMessage::~EventLogMessage()
{
#if defined(OS_WIN)
    // If g_event_source_name is nullptr (which it is per default) SYSLOG will
    // degrade gracefully to regular LOG. If you see this happening most probably
    // you are using SYSLOG before you called SetEventSourceName.
    if (g_event_source_name == nullptr)
        return;

    HANDLE event_log_handle = RegisterEventSourceA(NULL, g_event_source_name->c_str());
    if (event_log_handle == NULL) {
        stream() << " !!NOT ADDED TO EVENTLOG!!";
        return;
    }

    base::ScopedClosureRunner auto_deregister(
        base::Bind(base::IgnoreResult(&DeregisterEventSource), event_log_handle));
    std::string message(log_message_.str());
    WORD log_type = EVENTLOG_ERROR_TYPE;
    switch (log_message_.severity()) {
    case LOG_INFO:
        log_type = EVENTLOG_INFORMATION_TYPE;
        break;
    case LOG_WARNING:
        log_type = EVENTLOG_WARNING_TYPE;
        break;
    case LOG_ERROR:
    case LOG_FATAL:
        // The price of getting the stack trace is not worth the hassle for
        // non-error conditions.
        base::debug::StackTrace trace;
        message.append(trace.ToString());
        log_type = EVENTLOG_ERROR_TYPE;
        break;
    }
    LPCSTR strings[1] = { message.data() };
    if (!ReportEventA(event_log_handle, log_type, BROWSER_CATEGORY,
            MSG_LOG_MESSAGE, NULL, 1, 0, strings, NULL)) {
        stream() << " !!NOT ADDED TO EVENTLOG!!";
    }
#elif defined(OS_LINUX)
    const char kEventSource[] = "chrome";
    openlog(kEventSource, LOG_NOWAIT | LOG_PID, LOG_USER);
    // We can't use the defined names for the logging severity from syslog.h
    // because they collide with the names of our own severity levels. Therefore
    // we use the actual values which of course do not match ours.
    // See sys/syslog.h for reference.
    int priority = 3;
    switch (log_message_.severity()) {
    case LOG_INFO:
        priority = 6;
        break;
    case LOG_WARNING:
        priority = 4;
        break;
    case LOG_ERROR:
        priority = 3;
        break;
    case LOG_FATAL:
        priority = 2;
        break;
    }
    syslog(priority, "%s", log_message_.str().c_str());
    closelog();
#endif // defined(OS_WIN)
}

} // namespace logging
